Olefin polymerization process with alkyl-substituted metallocenes

ABSTRACT

The invention comprises an olefin polymerization process comprising contacting ethylene alone or with one or more olefinically unsaturated comonomers with a Group 3-6 metallocene catalyst compound comprising one π-bonded ring having a C 3  or greater hydrocarbyl, hydrocarbylsilyl or hydrocarbylgermyl substituent said substituent bonded to the ring through a primary carbon atom; and, where the compound contains two π-bonded rings, the total number of substituents on the rings is equal to a number from 3 to 10, said rings being asymmetrically substituted where the number of substituents is 3 or 4. The invention process is particularly suitable for preparing ethylene copolymers having an MIR less than about 35, while retaining narrow CD even at high comonomer incorporation rates, and with certain embodiments providing ethylene copolymers having improved melt strength with the low MIR.

RELATED APPLICATIONS

[0001] This application is a Divisional of Ser. No. 09/615,296 filed onJul. 13, 2000; U.S. Ser. No. 09/615,296 is a Divisional of U.S. Ser. No.09/400,568 filed on Sep. 21, 1999; 09/400,568 claims the benefit ofprovisional application Serial. No. 60/021,841 filed on Jul. 16, 1996.

FIELD OF THE INVENTION

[0002] The invention relates to a polymerization process forolefinically unsaturated monomers utilizing alkyl-substituent containingmetallocenes to achieve polymer products having narrow compositiondistributions, low melt index ratios, and, optionally, high meltstrength.

BACKGROUND OF THE INVENTION

[0003] The use of metallocene compounds in catalyst systems for thepolymerization of olefinically unsaturated olefins is well known in theart. Metallocene compounds have been defined as organometalliccoordination compounds obtained as a cyclopentadienyl derivative of atransition metal or metal halide. Three types are representative:biscyclopentadienyl Group 4 metal compounds, biscyclopentadienyl Group5-10 metal compounds and monocyclopentadienyl Group 4 and 5 metalcompounds. In these categories are included those havingalkyl-substituents on one or both cyclopentadienyl rings, both bridgedmetallocenes and unbridged metallocenes where the bridging if present isbetween one cyclopentadienyl ring ligand and another, or onecyclopentadienyl ring ligand and a heteroatom ligand of the transitionmetal. Syntheses of these compounds are well known and typicallycomprise the reaction of one or more selected cyclopentadienidecompounds with a transition metal halide.

[0004] Metallocenes generally are capable of narrow molecular weightdistributions (MWD) in view of their typically yielding single-sitecatalysts when activated. However, capabilities as to compositionaldistributions (CD) and melt index ratios (MIR) vary widely, particularlywhen the transition metal compounds are immobilized on particulatesupports so as to form heterogeneous catalyst systems. Polymer productsused in certain applications benefit from low MIR. The opticalproperties are improved when polymer fractions, typically comprised inthe polymerization reaction product of any coordination polymerizationcatalysts, are as similar as possible. Additionally, narrow CD polymerstypically have good optical properties, low levels of extractables andlow blocking attributes. The narrow CD also is indicative of narrowmelting point distribution which is of particular importance for filmmanufacturers.

[0005] Unbridged biscyclopentadienyl metallocene compounds having alkylsubstituents said to be suitable for olefin polymerization, particularlyheterogeneous polymerization process conditions, are described in U.S.Pat. No. 5,470,811. The catalysts comprise preferably at least two alkylsubstituents on each cyclopentadienyl ligand and provide broad molecularweight distribution, high molecular weight and narrow compositiondistributions. Table II examples 11-13 illustrate the use of(1,3-Me-n-BuCp)₂ZrCl₂, (1,2-Me-n-BuCp)₂ZrCl₂ and (n-Pr-Cp)₂ZrCl₂ forcopolymers having I₂₁/I₂ (defined as melt index ratio, MIR, measured inaccordance with ASTM D-1238) values from 17.9 to 23.2 and MWD(M_(w)/M_(n)) values of from 2.5 to 3.7. Utility of the copolymers infilm products and background for film preparation are disclosed. Seealso, WO 96/00246 for a description of multiply substitutedcyclopentadienyl ring-containing metallocenes and their use in gas phasepolymerization processes where low melt indices or high molecularweights are sought.

[0006] Bridged biscyclopentadienyl metallocenes useful for gas phasepolymerization are disclosed in European Patent Application 0 659 773A1. The cyclopentadienyl moieties may be substituted with one or moresubstituents R, the catalysts are said to be suitable for the productionof long chain branch-containing polyethylene when used in the processdescribed. Values for I₂₁/I₂ of 56 to 110 are illustrative of theinvention, the comparative examples illustrate values of 37 to 47.

SUMMARY OF THE INVENTION

[0007] The invention comprises an olefin polymerization processcomprising contacting ethylene alone or with one or more olefinicallyunsaturated comonomers with a Group 3-6 metallocene catalyst compoundcomprising one π-bonded ring having one or more C₃ or greaterhydrocarbyl, hydrocarbylsilyl or hydrocarbylgermyl substituent, saidsubstituent bonded to the ring through a primary carbon atom. Moreover,where the metallocene contains two π-bonded rings, the total number ofsubstituents on the rings is equal to a number from 3 to 10, and therings are incommensurately substituted when the number of substituentsis 3 or 4. In a preferred-embodiment compound containing two π-bondedrings, the rings are covalently bridged and a C₃ or greater hydrocarbyl,hydrocarbylsilyl or hydrocarbylgermyl substituent is at its ring 3 or 4position with respect to the bridge. Where the metallocene contains onlyone π-bonded ring, it will preferably be bridged to a Group 15 or 16heteroatom, in which the heteroatom is connected to at least onesecondary or tertiary, Group-14-atom containing hydrocarbyl,hydrocarbylsilyl or hydrocarbylgermyl substituent group of 1 to 20non-hydrogen atoms. The term substituent when referring to those groupssubstituted on the rings includes essentially hydrocarbyl,hydrocarbylsilyl or hydrocarbylgermyl groups having from about 1 to 30Group 14 atoms. Two adjacent ring substituent groups may be joined so asto form a fused ring system, for example, unsubstituted or furthersubstituted indenyl, fluorenyl or azulenyl groups. The invention processis particularly suitable for preparing ethylene copolymers having an MIRless than about 35, preferably less than about 30, and for certainembodiments less than about 20, and narrow CD, such as those having acomonomer distribution breadth index (CDBI) equal to or above 60, evenat high comonomer incorporation rates. Ethylene copolymers havingimproved melt strength while retaining the low MIR and narrow CD arealso enabled by use of invention metallocene compounds containing twoπ-bonded rings covalently bridged to each other, with the C₃ or greaterhydrocarbyl, hydrocarbylsilyl or hydrocarbylgermyl substituent beingbonded at the 3 or 4 position on one of the rings, where the ring carboncovalently bonded to the bridge is counted as the 1 position.

BRIEF DESCRIPTION OF THE FIGURES

[0008]FIG. 1 is a Differential Scanning Calorimetry (DSC) measurement ofpolymer made according to the invention in Example I.

[0009]FIG. 2 is a comparative DSC measurement of polymer made with acatalyst of the prior art. A comparison of the figures illustrates thenarrow melting point distribution achieved using the invention catalystexemplified.

DETAILED DESCRIPTION OF THE INVENTION

[0010] The preferred Group 4 catalyst compounds comprising one π-bondedring can be represented by the formula:

L^(A)L^(B)L^(C) _(i)MAD,  (1)

[0011] where L^(A)L^(B)L^(C) _(i)MAD is the invention transition metalmetallocene compound. More specifically, L^(A) is a substitutedcyclopentadienyl or heterocyclopentadienyl ancillary ligand π-bonded toM; L^(B) can be a member of the class of ancillary ligands defined forL^(A), or can be J, a heteroatom ancillary ligand C-bonded to M; theL^(A) and L^(B) ligands may be covalently bridged together through aGroup 14 element linking group, preferably the Group 14 element beingcarbon or silica; L^(C) _(i) is an optional neutral, non-oxidizingligand having a dative bond to M (typically i equals 0 to 3) M is aGroup 4 transition metal; and, A and D are independently monoanioniclabile ligands, optionally bridged to each other or L^(A) or L^(B), eachhaving a σ-bond to M which can be broken for abstraction purposes, by asuitable activator and into which a polymerizable monomer ormacromonomer can insert for coordination polymerization, or are ligandswhich can be converted to such. At least one of L^(A) or L^(B) has atleast one C₃ or greater hydrocarbyl, hydrocarbylsilyl orhydrocarbylgermyl substituent bonded to the ring through a primarycarbon atom.

[0012] Either of L^(A) or L^(B) may be a cyclopentadienyl-groupcontaining ring which is substituted with from two to five substituentgroups R. When both are cyclopentadienyl-group containing rings, L^(A)or L^(B) may be a cyclopentadienyl ring with one substituent and theother a substituted cyclopentadienyl ring with two or more substituents.Each substituent group R is, independently, a radical selected fromhydrocarbyl, hydrocarbylsilyl or hydrocarbylgermyl having from 1 to 20carbon, silicon or germanium atoms, substituted hydrocarbyl,hydrocarbylsilyl or hydrocarbylgermyl radicals as defined wherein one ormore hydrogen atoms is replaced by a halogen radical, an amido radical,a phosphido radical, an alkoxy radical, an aryloxy radical or any otherradical containing a Lewis acidic or basic functionality; C₁ to C₂₀hydrocarbyl-substituted metalloid radicals wherein the metalloid isselected from the Group IV A of the Periodic Table of Elements; halogenradicals; amido radicals; phosphido radicals; alkoxy radicals; oralkylborido radicals or, either of L^(A) or L^(B) may be acyclopentadienyl ring in which at least two adjacent R-groups are joinedtogether and along with the carbon atoms to which they are attached forma C₄ to C₂₀ ring system which may be saturated, partially unsaturated oraromatic, and substituted or unsubstituted, the substitution being ofone or more R groups as defined above.

[0013] Either or both of L^(A) or L^(B) may similarly be aheterocyclopentadienyl ancillary ligand π-bonded to M. The term“heterocyclopentadienyl” means here a 5-member ring analogous to acyclopentadiene ring wherein at least one carbon atom at any position inthe ring has been replaced with a non-carbon Group 14 or 15 element.Preferably the non-carbon elements are selected from the groupconsisting of germanium, silicon, nitrogen or phosphorous. The Group 14or Group 15 heterocyclopentadienyl moieties are analogous to acyclopentadienyl moiety which possesses a formal charge −1, making itformally a monoanionic ligand. And, though cyclopentadienyl rings aretypically described as being “eta-5” bonded to the transition metal inmetallocenes, other forms of π-bonding, eta-3 through eta-4, mayadditionally be possible with the Group 14 or 15 heterocyclopentadienylligands of the invention and thus are included within the scope of theinvention. For purposes of this disclosure, “eta-5” means that thecyclopentadiene ring is connected to the metal through all five of thering atoms in an essentially equivalent manner. Suchheterocyclopentadienyl ligands are addressed in U.S. Pat. No. 5,434,116,International publication WO 95/04087, Japanese application 08-24751 andco-pending application U.S. serial No. 60/041258 filed Mar. 17, 1997,each is incorporated by reference for purposes of U.S. patent practice.

[0014] The C₃ or greater hydrocarbyl, hydrocarbylsilyl orhydrocarbylgermyl substituent bonded to either the L^(A) or L^(B) ringthrough a primary carbon atom is preferably an n-alkyl substituent, suchas, n-propyl, n-butyl, n-pentyl, n-dodecyl, etc. Substituents having aprimary carbon attached to the ring may be branched after that carbon,examples include 2-ethylbutyl, 2-methylpropyl, 2-cyclohexylethyl, andbenzyl. The primary-carbon-containing substituent is attached to eitherof the L^(A) or L^(B) rings and is preferably the only substituent onthe ring to which it is attached, or is the substituent with thegreatest number of non-hydrogen atoms. Additionally, for inventioncompounds containing a Group 14 atom-containing bridging group betweenthe L^(A) and L^(B) rings, the C₃ or greater, primary carbon-containingsubstituent of the invention is preferably located at the 3 or 4position, counting from the atom in the ring covalently bonded to thebridge, preferably the 3 position.

[0015] J as referred to above is a Group 15 or 16 heteroatom which maybe substituted with one R′ group when J is a group 15 element and J iscovalently bridged to L^(A), or with two R′ groups when J is a group 15element and J is not covalently bridged to L^(A), or is unsubstitutedwhen J is a Group 16 element and J is covalently bridged to L^(A), andeach substituent group R′ is, independently, a radical selected from:hydrocarbyl, hydrocarbylsilyl or hydrocarbylgermyl radicals having 1 to30 carbon, silicon or germanium atoms; substituted hydrocarbyl,silyl-hydrocarbyl or germyl-hydrocarbyl radicals as defined wherein oneor more hydrogen atoms is replaced by a C₁₋₂₀ hydrocarbyl radical,halogen radical, an amido radical, a phosphido radical, an alkoxyradical, or an aryloxy radical; halogen radicals; amido radicals;phosphido radicals; alkoxy radicals; or alkylborido radicals. Apreferred J group when unbridged to L^(A) is one where each R′ isindependently a bulky substituent such as tert-butyl or trimethyl silyl,see copending application U.S. application Ser. No. 08/833,146, filedApr. 4, 1997, and filed internationally as PCT/US96/17224, incorporatedby reference for purposes of U.S. patent practice.

[0016] The term “incommensurate” as applied for two L^(A) and L^(B)rings means, for the purposes of this description and the claims derivedtherefrom, the number or type of ring substituents on the L^(A) andL^(B) rings is different. Thus for certain embodiments of the inventionmetallocene catalyst compound containing two π--bonded rings and a totalnumber of substituents on the rings equal to 3, two generally definedsubstituents can be on L^(A) and the primary-carbon-containingsubstituent of the invention then is on the L^(B) ring. For certainembodiments of the invention metallocene catalyst compound containingtwo π-bonded rings and a total number of substituents on the rings equalto 4, three generally defined substituents can be on L^(A) and theprimary carbon-containing substituent of the invention is on the L^(B)ring. Preferred illustrative embodiments include:(tetramethyl-cyclopentadienyl)(n-propyl-cyclopentadienyl) zirconiumdichloride or dimethyl,(pentamethyl-cyclopentadienyl)(n-propyl-cyclopentadienyl) zirconiumdichloride or dimethyl,(tetramethyl-cyclopentadienyl)dimethylsilyl(3-n-propyl-cyclopentadienyl)zirconium dichloride or dimethyl,(tetrahydroindenyl)dimethylsilyl(3-n-propyl-cyclopentadienyl) zirconiumdichloride or dimethyl,(tetramethyl-cyclopentadienyl)dimethylsilyl(2-methyl-4-n-propylcyclopentadienyl)zirconium dichloride or dimethyl,(indenyl)isopropylidene(3-n-propyl-cyclopentadienyl) zirconiumdichloride or dimethyl,(indenyl)dimethylsilyl(3-n-propyl-cyclopentadienyl) hafnium dichlorideor dimethyl, (1,3-dimethyl-cyclopentadienyl) (n-butyl-cyclopentadienyl)zirconium dichloride or dimethyl,(tetramethyl-3-n-propylcyclopentadienyl)(cyclopentadienyl) zirconiumdichloride or dimethyl,(1-methyl-2-n-butylcyclopentadienyl)(methylcyclopentadienyl) zirconiumdichloride ordimethyl,(1-methyl-3-ethylcyclopentadienyl)(1-methyl-3-n-propylcyclopentadienyl)zirconocene, (1,2,4-trimethyl-3,5-di-n-butylcyclopentadienyl) zirconiumdichloride or dimethyl, (1-n-butylindenyl)(4-phenylindenyl) zirconiumdichloride or dimethyl and(indenyl)dimethylsilyl(3-n-propyl-cyclopentadienyl) hafnium dichlorideor dimethyl. In general methyl groups are the preferred complementaryring substituents for both the bridged and unbridged embodiments, thatis in addition to the a C₃ or greater substituent bonded to one ringthrough a primary carbon atom. Where fused rings are part of the ringsubstitution pattern each such fused ring is counted as two substituentson its respective cyclopentadienyl ring. Thus indenyl ligands areconsidered to be cyclopentadienyl rings having two substituents andfluorenyl ligands are considered to be cyclopentadienyl rings havingfour substituents. Additional substituents on the fused rings are notindependently counted in determining the number of substituents on thecyclopentadienyl ring, but are taken into consideration in determiningincommensurateness.

[0017] The catalyst compounds described above are suitable for olefinpolymerization in accordance with known polymerization processes forwhich art-recognized metallocene catalysts have been shown to besuitable. The patent art with respect to both monocyclopentadienyl andbiscyclopentadienyl catalysts will be instructive. See, for example,U.S. Pat. Nos. 5,198,401, 5,324,800, 5,502,124, 5,635,573, 5,536,796 andInternational publications WO 92/00333 and WO 96/33227. Generallyspeaking, the polymerization process comprises contacting one or moreolefinically unsaturated monomers with an activated catalyst compound ofthe invention, activation occurring by reaction or interaction with acocatalyst activator compound suitable for activation of knownmetallocene compounds into active, insertion polymerization catalystcompounds. The teachings as to olefin polymerization in the referencesabove are incorporated by reference for purposes of U.S. patentpractice. As is well-known in the art, suitable polymerizable olefinsinclude α-olefins containing 2 or more carbon atoms, preferably C₂ to C₈α-olefins, cyclic olefins, preferably norbornene or alkyl-substitutednorbomenes, non-conjugated diolefins, and vinyl aromatic monomers,preferably styrene and alkyl-substituted styrene monomers. Additionally,when the invention metallocene contains only one π-bonded ring bridgedto a Group 15 or 16 heteroatom, geminally disubstituted olefins, such asisobutylene, will be polymerizable in accordance with the teachings ofU.S. application Ser. No. 08/651,030, filed on May 21, 1996,incorporated by reference for purposes of U.S. patent practice.

[0018] The catalysts according to the invention are particularly suitedto use in known gas phase or slurry copolymerization processes whereheterogeneous catalysts are typically used. The heterogeneous catalystsof the invention are typically supported on inert support particles,which may be formed from inorganic refractory oxide or from polymericmaterials, which are then used in a gas phase or liquid process whereinthe monomers are contacted with the supported catalysts. The teachingsand descriptions of the background art are incorporated by reference forpurposes of U.S. patent practice and are specific to process conditionsand reagents useful with the catalyst system of this invention.

[0019] For olefin polymerization, the metallocene compounds of theinvention may be activated by use of the traditional activationcocatalysts, specifically including the use of alkyl aluminum compounds,alkyl alumoxane compounds and any ionizing activators, such as thoserepresented by aryl-substituted boron compounds, e.g.,nitrogen-containing salts, carbenium or phosphonium salts, metal saltsand neutral Lewis acid compounds. Each activation method iswell-documented in the field of metallocene art. Related means ofactivation, such as the use of alkyl aluminum alkylation agents used toconvert metallocene halide compounds to hydride or alkylgroup-containing compounds prior to activation with the ionic activatorcompounds will be suitable in accordance with the inventions.Additionally, the use of supported activators, where such are stablecompounds, will be suitable in accordance with the invention for bothactivation and support. See, for example, U.S. Pat. Nos. 5,427,991 and5,643,847, each of which is incorporated by reference for purposes ofU.S. patent practice.

[0020] The use of organometallic compounds as scavenging compounds inthe olefin polymerization processes of the invention will also besuitable. Alkyl aluminum compounds such as triethyl aluminum,triisobutyl aluminum, tri-n-octyl aluminum, methylalumoxane andisobutylalumoxane are well-known in the art.

[0021] Suitable gas phase processes are illustrated U.S. Pat. Nos.4,543,399, 4,588,790, 5,028,670, 5,352,749, 5,382,638, 5,405,922,5,422,999, 5,436,304, 5,453,471, and 5,463,999, and Internationalapplications WO 94/28032, WO 95/07942 and WO 96/00245. Each isincorporated by reference for purposes of U.S. patent practice.Typically the processes are conducted at temperatures of from about−100° C. to 150° C., preferably from about 40° C. to 120° C., atpressures up to about 7000 kPa, typically from about 690 kPa to 2415kPa. Continuous processes using fluidized beds and recycle streams asthe fluidizing medium are preferred.

[0022] Slurry polymerization processes in which the immobilized catalystsystems of this invention may be used are typically described as thosein which the polymerization medium can be either a liquid monomer, likepropylene, or a hydrocarbon solvent or diluent. Aliphatic paraffin suchas propane, isobutane, hexane, heptane, cyclohexane, etc. or an aromaticsolvent such as toluene can be advantageously employed. Thepolymerization temperatures may be those considered low, e.g., less than50° C., preferably 0-30° C., or may be in a higher range, such as up toabout 150° C., preferably from 50° C. up to about 80° C., or at anyranges between the end points indicated. Pressures can vary from about100 to about 700 psia (0.76-4.8 Mpa). Additional description is given inU.S. Pat. Nos. 5,274,056 and 4,182,810 and WO 94/21962 which areincorporated by reference for purposes of U.S. patent practice.

[0023] The immobilized catalyst systems of the invention may be preparedby any effective method of supporting other coordination catalystsystems, effective meaning that the catalyst so prepared can be used forpreparing polymer in a heterogeneous polymerization process. Preferredmethods include those referred to in copending U.S. application Ser. No.08/466,547, filed Jun. 6, 1995, and in its counterpart WO 96/00245. Inaccordance with this method, as illustrated in the examples below, thetransition metal compound is combined with an activator compound insolvent to prepare a precursor solution which is added to a poroussupport particle in such a manner that the total solvent volume exceedsthe total particle pore volume but is less than that at which theformation of a slurry is observed.

[0024] The activated catalyst may also be supported in accordance withWO 91/0882 and WO 94/03506, particularly when using ionizing activatorsproviding electronically stabilizing non-coordinating anions. In thismethod, inorganic oxide particle supports are treated with a Lewis acidto neutralize any hydroxyl groups remaining on the surfaces afterthorough drying and prior to the adsorption of the activated catalystcomplex from the solution in which it is added.

[0025] The support method of Example 11-16 in copending U.S. applicationSer. No. 08/549,991, filed Oct. 30, 1995, and in WO 96/08520 will alsobe suitable in accordance with this invention.

[0026] Additional methods appear in the following descriptions formetallocene catalysts, these methods will be suitable as well for theinvention catalyst systems. U.S. Pat. No. 4,937,217 generally describesa mixture of trimethylaluminum and triethylaluminum added to anundehydrated silica to which a metallocene catalyst component is thenadded. EP-308177-B1 generally describes adding a wet monomer to areactor containing a metallocene, trialkylaluminum and undehydratedsilica. U.S. Pat. Nos. 4,912,075, 4,935,397 and 4,937,301 generallyrelate to adding trimethylaluminum to an undehydrated silica and thenadding a metallocene to form a dry supported catalyst system. U.S. Pat.No. 4,914,253 describes adding trimethylaluminum to undehydrated silica,adding a metallocene and then drying the resulting supported catalystsystem with an amount of hydrogen to produce a polyethylene wax. U.S.Pat. Nos. 5,008,228, 5,086,025 and 5,147,949 generally describe forminga dry supported catalyst system by the addition of trimethylaluminum toa water impregnated silica to form alumoxane in situ and then adding themetallocene. U.S. Pat. Nos. 4,808,561, 4,897,455 and 4,701,432 describetechniques to form a supported catalyst where the inert carrier,typically silica, is calcined and contacted with a metallocene(s) and anactivator/cocatalyst component. U.S. Pat. No. 5,238,892 describesforming a dry supported catalyst system by mixing a metallocene with analkyl aluminum and then adding undehydrated silica. U.S. Pat. No.5,240,894 generally pertains to forming a supportedmetallocene/alumoxane catalyst system by forming a metallocene/alumoxanereaction solution, adding a porous carrier, and evaporating theresulting slurry to remove residual solvent from the carrier.

[0027] Polymeric carriers will also be suitable in accordance with theinvention, see for example the descriptions in WO 95/15815 and U.S. Pat.No. 5,427,991. As taught for metallocene catalysts in these documents,the catalyst complexes of this invention may be either adsorbed orabsorbed, on the polymeric supports, particularly if made up of porousparticles, or may be chemically bound through functional groupscovalently bound to or in the polymer chains.

[0028] Suitable solid particle supports are typically comprised ofpolymeric or refractory oxide materials, each being preferably porous.Any support material, preferably a porous support material, such as forexample, talc, inorganic oxides, inorganic chlorides, for examplemagnesium chloride and resinous support materials such as polystyrenepolyolefin or polymeric compounds or any other organic support materialand the like that has an average particle size preferably greater than10 μm is suitable for use in this invention.

[0029] The preferred support materials are inorganic oxide materials,which include those from the Periodic Table of Elements of Groups 2, 3,4, 5, 13 or 14 metal or metalloid oxides. In a preferred embodiment, thecatalyst support materials include silica, alumina, silica-alumina, andmixtures thereof. Other inorganic oxides that may be employed eitheralone or in combination with the silica, alumina or silica-alumina aremagnesia, titania, zirconia, and the like.

[0030] It is preferred that the catalyst support materials have asurface area in the range of from about 10 to about 700 m²/g, porevolume in the range of from about 0.1 to about 4.0 cc/g and averageparticle size in the range of from about 10 to about 500 μm. Morepreferably, the surface area is in the range of from about 50 to about500 m²/g, pore volume of from about 0.5 to about 3.5 cc/g and averageparticle size of from about 20 to about 200 μm. Most preferably thesurface area range is from about 100 to about 400 m²/g, pore volume fromabout 0.8 to about 3.0 cc/g and average particle size is from about 30to about 100 μm. The pore size of the carrier of the invention typicallyhas pore size in the range of from 10 to 1000 Angstroms, preferably 50to about 500 Angstroms, and most preferably 75 to about 350 Angstroms.

[0031] The above documents typically discuss specific methods ofsupporting metallocene catalysts. Generally the procedures that followwill be suitable. An aluminoxane, such as methylalmoxane or modifiedalumoxane, or other suitable cocatalyst activator such as Al(CH₃)₃,Al(CH₂CH₃)₂Cl, B(C₆F₅)₃, [C₆H₅NMe₂H][B(C₆F₅)₄], [(C₆H₅)₃C][B(C₆F₅)₄],[H][PF₆], [Ag][BF₄], [Ag][PF₆], or [Ag][B(C₆F₅)₄] is combined with oneor more transition metal complexes in an appropriate solvent to form aprecursor solution. A suitable support, preferably porous, is charged toa vessel and the precursor solution is added with stirring. The mixturemay be mixed by hand with a spatula, by a rotating stirrer with wireloops such as a Kitchen Aid dough mixer, by metal blades rotating athigh speed such as in a Wehring blender, by a helical ribbon bladedmixer, by shaking, tumbling, fluidized bed mixing, by paddle orpropeller blades on a rotating stir shaft, or other appropriate means.The total amount of solvent used to form the precursor suspension orsolution may be less than the pore volume of the support as inimpregnation to incipient wetness, or greater than the pore volume ofthe support such that a slurry is formed, or an amount in between suchthat a solution-finely divided support mixture is neither free flowingnor a slurry. Solution may be added to support or vice versa asappropriate to the mixing method. If desired the liquids may be removedby purging with an inert gas or under vacuum.

[0032] The products of the polymerization processes described above,using the invention catalyst compounds, are typically those havingnarrow composition distribution (CDBI≧60) with melt index ratios lessthan about 35, preferably 30 and more preferably less than about 25. TheMWD (M_(w)/M_(n)) can range from about 2-15, preferably 2-10, and even2.5-5. Where greater than about 4.5, melt processing of the copolymerproducts are improved; where less than 4.5 end-product clarity anduniformity are improved. The molecular weight, as expressed in terms ofits polyethylene melt index (MI; 2.16 kg/cm², 190° C., ASTM D 1238) willtypically range from 0.2 to 10 as determined by specific catalyst choiceand selection of known operating polymerization conditions such ashydrogen addition and polymerization temperature. It has beenadditionally observed that ethylene copolymers having high melt strength(MS; ≧6.0-6.0× log (MI), preferably ≧8.0-6.0× log (MI)) are madepossible with certain catalysts of the invention, this beingparticularly surprising in that high melt index ratios (MIR; I₂₁/I₂)values (e.g., ≧35) previously had been thought to be a necessaryparameter for achieving high values of melt strength. As illustrated inexample 14 below, bridged, biscyclopentadienyl catalyst compoundsaccording to the invention can yield a surprising combination of low MIRand high melt strength. This combination results in improved bubblestrength for blown film and reduced problems with “neck in” for cast orextruded film without the expected significant reduction of filmtoughness typically observed with ethylene polymers having high MIR andhigh MS.

[0033] The polymer characterizations presented in this application wereconducted under the following conditions and procedures. MI wasdetermined as described above. MIR is described as the ratio of the I₂₁to I₂ in accordance with ASTM D-1238. All of M_(w), M_(n), andM_(w)/M_(n) (MWD) were determined by gel permeation chromatography (GPC)using a DRI differential refraction index detector, i.e., a Waters 150CGPC instrument with DRI detectors. CDBI was determined in accordancewith the method described in columns 7 and 8 of WO 93/03093. Meltstrength was determined using a Gottfert Rheotens Melt Strengthapparatus measuring at 190° C. in conjunction with an Instron CapillaryRheometer. The capillary die was set at 0.6 in. diameter×1 in. lengthand the extrudate rate was set at the die exit at 3 in./min. The takeoff gears of the apparatus were set at 100 mm from the die exit. Thetake-up speed for the extrudate was progressively increased inaccordance with the program of an Acceleration Programmer Model 459117at a setting of 12. Density was measured in accordance with ASTM d-1505.The Average Particle Size (APS) was measured by determining the weightof material collected on a series of U.S. Standard sieves anddetermining the weight average particle size in micrometers based on thesieve series used.

EXAMPLES

[0034] I. Unbridged Biscyclopentadienyl Catalyst Systems

Example 1 (Invention) (n-propylcyclopentadienyl)(pentamethylcyclopentadienyl) Zirconium Dichloride

[0035] Metallocene Synthesis.

[0036] Pentamethylcyclopentadienyl zirconium trichloride (25 g, 75 mmol)was dissolved in 200 cm³ of a 50:50 mixture of toluene andtetrahydrofuran. The reaction flask was equipped with a mechanicalstirrer and cooled to −78° C. 75 cm³ of 1.0 M solution ofsodium-n-propylcyclopentadienide (corresponding to 75 mmoln-propylcyclopentadiene) in toluene/tetrahydrofuran was then addedslowly using a pressure-equilibrated addition funnel. The reaction wasallowed to continue over 16 hours while the temperature warmed to 22° C.The solvent was then removed under reduced pressure at 45° C. Theresulting crude product was extracted repeatedly with hexane. The hexaneextracts were concentrated and the pure (n-propycyclopentadienyl)(pentamethyl cyclopentadienyl) zirconium dichloride was precipitated outat −34° C. The purity of the compound was confirmed with ¹H-NMR (500MHz).

[0037] Preparation of Supported Catalyst.

[0038] a) Methylalumoxane (1091 cm³ of 30 wt-% solution in toluene) wascharged into a 2-gallon reaction vessel. 1576 cm³ of fresh toluene wasadded. Then a 10 wt-% solution of 14.8 g of(n-propylcyclopentadienyl)(pentamethylcyclopentadienyl) zirconiumdichloride in toluene was added. The temperature was maintained at 27°C. and the mixture stirred for 1 hour.

[0039] b) 800 g of a Davison 948 sample dehydrated at 600° C. wascharged into a 2-gallon reaction vessel at 27° C. The solution ofmethylalumoxane and metallocene from above was added onto the silica intwo equal portions. Then an additional 450 cm³ toluene was added to theslurry. After 20 minutes, a solution of 5.7 g ofN,N-bis(2-hydroxylethyl) octadecylamine in 50 cm³ toluene was added andstirring continued for another 30 minutes. The final catalyst was thendried to free-flowing powder at 80° C. under vacuum.

[0040] Polymerization.

[0041] The supported catalyst described above was then tested in a pilotplant. The catalyst was fed continuously into a fluid bed gas-phasepilot plant reactor (internal diameter of 161/4 inches) maintained at85° C. and 300 psig total reactor pressure. The product was withdrawncontinuously through a product discharge outlet to maintain a constantbed height in the reactor. The composition of the gas phase, andoperating conditions for the reactor, are summarized in Table I below.

Example 2 (n-propylcyclopentadienyl)-(pentamethylcyclopentadienyl)Zirconium Dichloride

[0042] 550 g of a Davison 948 sample dehydrated at 200° C. was chargedinto a 2-gallon reaction vessel at 27° C. 1280 cm³ of a 30 wt-%methylalumoxane solution in toluene was added followed by 1500 cm³ freshtoluene. The temperature was then raised to 68° C. and stirringcontinued for 4 hours. 26.7 g of(n-propylcyclopentadienyl)-(pentamethylcyclopentadienyl) zirconiumdichloride in 100 cm³ toluene was then added and stirring continued foran additional 2 hours. The final catalyst was dried to free-flowingpowder under vacuum at 68° C.

[0043] The supported catalyst was used in the polymerization of ethylenewith 1-hexene in a gas-phase pilot unit as described in example 1 exceptthat triethylaluminum was used as scavenger during the polymerization.The results are shown in Table I below.

Comparative Example 3 bis(n-propylcyclopentadienyl) Zirconium Dichloride

[0044] Preparation of Supported Catalyst.

[0045] a) Methylalumoxane (1070 cm³ of 30 wt-% solution in toluene) wascharged into a 2-gallon reaction vessel. 1611 cm³ of fresh toluene wasadded. Then a 10 wt-% solution of 13.5 g ofbis(n-propylcyclopentadienyl) zirconium dichloride in toluene was added.The temperature was maintained at 27° C. and the mixture stirred for 1hour.

[0046] b) 800 g of a Davison 948 sample dehydrated at 600° C. wascharged into a 2-gallon reaction vessel at 27° C. The solution ofmethylalumoxane and metallocene from above was added onto the silica intwo equal portions. Then an additional 450 cm³ toluene was added to theslurry. After 20 minutes, a solution of 5.7 g ofN,N-bis(2-hydroxylethyl) octadecylamine in 50 cm³ toluene was added andstirring continued for another 30 minutes. The final catalyst was thendried to free-flowing powder at 80° C. under vacuum.

[0047] Polymerization.

[0048] The supported catalyst was used in the polymerization of ethylenewith 1-hexene in a gas-phase pilot unit as described in example 1. Theresults are shown in Table I below. Though illustrating low MIR polymerproducts, the comparison of FIGS. 1 and 2 illustrate that the polymer ofEx. 3 has a dual melting point peak instead of the single melting pointpeak of the polymers from the invention catalysts. The second melt DSCtraces of FIGS. 1 and 2 were obtained on a Perkin-Elmer instrument usingASTM D3417-83 standard procedures. TABLE I Example 1 2 3(C) Ethylene(mol %) 50 50 49.6 1-Hexene (mol %) 1.97 0.89 1.20 Hydrogen (ppm) 100126 279 Nitrogen balance balance balance Catalyst Productivity (g/g)4302 3720 9193 Melt Index (I₂) 1.02 2.33 2.81 Melt Index Ratio 15 20.918 (MIR) (I₂/I₂₁) Resin Density 0.9162 0.9220 0.9124 Polymer APS (μm)910 579 1181

Example 4 (Invention)(n-propylcyclopentadienyl)(pentamethylcyclopentadienyl) ZirconiumDichloride

[0049] Preparation of Supported Catalyst:

[0050] a) Methylalumoxane (1361 cm³ of 30 wt-% solution in toluene) wascharged into a 2-gallon reaction vessel. 1970 cm³ of fresh toluene wasadded. Then a solution of 18.5 g of (n-propylcyclopentadienyl)(pentamethylcyclopentadienyl) zirconium dichloride in 335 cm³ toluenewas added. The temperature was maintained at 27° C. and the mixturestirred for 1 hour.

[0051] b) 1000 g of a Davison 948 sample dehydrated at 600° C. wascharged into a 2-gallon reaction vessel at 27° C. The solution ofmethylalumoxane and metallocene from above was added onto the silica intwo equal portions. Then an additional 250 cm³ toluene was added to theslurry. After 20 minutes, a solution of 6.8 g ofN,N-bis(2-hydroxylethyl) octadecylamine in 70 cm³ toluene was added andstirring continued for another 20 minutes. The final catalyst was thendried to free-flowing powder at 68° C. under vacuum.

[0052] Polymerization:

[0053] The catalyst was then tested for ethylene/1-hexeneco-polymerization in a continuous fluid bed gas-phase reactor operatedat 300 psig total pressure, 79.4° C. reactor temperature, and 1.6 ft/scycle gas velocity. The catalyst was fed at a rate that maintained aconstant rate of product discharge from the reactor. The reactor gasmixture was composed of 35% ethylene, 1.08% 1-hexene and 90 ppm H₂.Sample was collected after 5 bed-turnovers and analyzed for propertiesshown in Table II below.

Example 5 (Invention)(n-butylcyclopentadienyl)(pentamethylcyclopentadienyl) ZirconiumDichloride

[0054] Preparation of Supported Catalyst:

[0055] A solution of methylalumoxane (MAO) and metallocene was formed byadding 55 cm³ of 30 wt-% MAO solution in toluene onto 0.895 g of(n-butylcyclopentadienyl) (pentamethylcyclopentadienyl) zirconiumdichloride in a vial. 120 cm³ of fresh toluene was added, and themixture stirred for 45 minutes at 25° C. This pre-mixed solution of theMAO and the metallocene was then added onto 40 g of Davison 948 silicadried to 600° C. The resulting slurry was stirred for 1 hour at 25° C.Then a solution of 0.28 g of N,N-bis(2-hydroxylethyl) octadecylamine in20 cm³ toluene was added, and stirring continued for another 30 minutes.The final catalyst was then dried to free-flowing powder under vacuum at65° C.

[0056] Polymerization:

[0057] The catalyst was then tested for ethylene/1-hexeneco-polymerization in the continuous fluid bed gas-phase reactor ofexample 4 operated at 300 psig total pressure, 79.4° C. reactortemperature, and 1.6 ft/s cycle gas velocity. The catalyst was fed at arate that maintained a constant rate of product discharge from thereactor. The reactor gas mixture was composed of 35% ethylene, 1.08%1-hexene and 84 ppm H₂. Sample was collected after 5 bed-turnovers andanalyzed for properties shown in Table II below.

Example 6 (Comparative)(methylcyclopentadienyl)(pentamethylcyclopentadienyl) ZirconiumDichloride

[0058] Preparation of Supported Catalyst:

[0059] A solution of methylalumoxane (MAO) and metallocene was formed byadding 27 cm³ of 30 wt-% MAO solution in toluene onto 0.343 g of(methylcyclopentadienyl) (pentamethylcyclopentadienyl) zirconiumdichloride in a vial. 100 cm³ of fresh toluene was added, and themixture stirred for 45 minutes at 25° C. This pre-mixed solution of theMAO and the metallocene was then added onto 20 g of Davison 948 silicadried to 600° C. The resulting slurry was stirred for 1 hour at 25° C.Then a solution of 0.15 g of N,N-bis(2-hydroxylethyl) octadecylamine in20 cm³ toluene was added, and stirring continued for another 30 minutes.The final catalyst was then dried to free-flowing powder under vacuum at65° C.

[0060] Polymerization:

[0061] The catalyst was then tested for ethylene/1-hexeneco-polymerization in the above continuous fluid bed gas-phase reactoroperated at 300 psig total pressure, 76.7° C. reactor temperature, and0.66 ft/s cycle gas velocity. The catalyst was fed at a rate thatmaintained a constant rate of product discharge from the reactor. Thereactor gas mixture was composed of 35% ethylene, 1.13% 1-hexene and 147ppm H₂. Sample was collected after 5 bed-turnovers and analyzed forproperties shown in Table II below.

Example 7 (Invention) (n-propylcyclopentadienyl)(tetramethylcyclopentadienyl) Zirconium Dichloride

[0062] Preparation of Supported Catalyst:

[0063] a) Methylalumoxane (1361 cm³ of 30 wt-% solution in toluene) wascharged into a 2-gallon reaction vessel. 1970 cm³ of fresh toluene wasadded. Then a solution of 18.0 g of (n-propylcyclopentadienyl)(tetramethylcyclopentadienyl) zirconium dichloride in 335 cm³ toluenewas added. The temperature was maintained at 27° C. and the mixturestirred for 1 hour.

[0064] b) 1000 g of a Davison 948 sample dehydrated at 600° C. wascharged into a 2-gallon reaction vessel at 27° C. The solution ofmethylalumoxane and metallocene from above was added onto the silica intwo equal portions. Then an additional 250 cm³ toluene was added to theslurry. After 20 minutes, a solution of 6.8 g ofN,N-bis(2-hydroxylethyl) octadecylamine in 70 cm³ toluene was added andstirring continued for another 20 minutes. The final catalyst was thendried to free-flowing powder at 68° C. under vacuum.

[0065] Polymerization:

[0066] The catalyst was then tested for ethylene/1-hexeneco-polymerization in a the above continuous fluid bed gas-phase reactoroperated at 300 psig total pressure, 79.4° C. reactor temperature, and1.6 ft/s cycle gas velocity. The catalyst was fed at a rate thatmaintained a constant rate of product discharge from the reactor. Thereactor gas mixture was composed of 35% ethylene, 0.87% 1-hexene and 103ppm H₂. Sample was collected after 5 bed-turnovers and analyzed forproperties shown in Table II below.

Example 8 (Comparative) (cyclopentadienyl) (tetramethylcyclopentadienyl)Zirconium Dichloride

[0067] Preparation of Supported Catalyst:

[0068] A solution of methylalumoxane (MAO) and metallocene was formed byadding 27 cm³ of 30 wt-% MAO solution in toluene onto 0.317 g of(cyclopentadienyl) (tetramethylcyclopentadienyl) zirconium dichloride ina vial. 100 cm³ of fresh toluene was added, and the mixture stirred for45 minutes at 25° C. This pre-mixed solution of the MAO and themetallocene was then added onto 20 g of Davison 948 silica dried to 600°C. The resulting slurry was stirred for 1 hour at 25° C. Then a solutionof 0.15 g of N,N-bis(2-hydroxylethyl) octadecylamine in 20 cm³ toluenewas added, and stirring continued for another 30 minutes. The finalcatalyst was then dried to free-flowing powder under vacuum at 65° C.

[0069] Polymerization:

[0070] The catalyst was then tested for ethylene/1-hexeneco-polymerization in the above continuous fluid bed gas-phase reactoroperated at 300 psig total pressure, 71.1° C. reactor temperature, and0.67 ft/s cycle gas velocity. The catalyst was fed at a rate thatmaintained a constant rate of product discharge from the reactor. Thereactor gas mixture was composed of 30% ethylene, 0.91% 1-hexene and 267ppm H₂. Sample was collected after 5 bed-turnovers and analyzed forproperties shown in Table II below.

Example 9 (Comparative) (methylcyclopentadienyl)(tetramethylcyclopentadienyl) Zirconium Dichloride

[0071] Preparation of Supported Catalyst:

[0072] A solution of methylalumoxane (MAO) and metallocene was formed byadding 13.6 cm³ of 30 wt-% MAO solution in toluene onto 0.1932 g of(methylcyclopentadienyl) (tetramethylcyclopentadienyl) zirconiumdichloride in a vial. 20 cm³ of fresh toluene was added, and the mixturestirred for 45 minutes at 25° C. This pre-mixed solution of the MAO andthe metallocene was then added onto 10 g of Davison 948 silica dried to600° C. The resulting slurry was stirred for 1 hour at 25° C. Then asolution of 0.0699 g of N,N-bis(2-hydroxylethyl) octadecylamine in 20cm³ toluene was added, and stirring continued for another 30 minutes.The final catalyst was then dried to free-flowing powder under vacuumat65° C.

[0073] Polymerization:

[0074] The catalyst was tested for the co-polymerization ofethylene/1-butene in a semi-batch gas-phase reactor at 85° C. Thepressure in the reactor was held constant by continuously feeding 5mol-% 1-butene in ethylene to compensate for any pressure change due topolymerization. After 1 h, the polymer formed was separated from theseed bed material and analyzed for resin molecular properties shown inTable II below.

Example 10 (Invention) (n-propylcyclopentadienyl)(pentamethylcyclopentadienyl) Zirconium Dichloride

[0075] Polymerization:

[0076] The supported catalyst made as in Example 1 above was tested forethylene/1-hexene co-polymerization in a batch slurry reactor usingisobutane as diluent. The reactor was operated at 325 psig totalpressure, 130 psi ethylene partial pressure, and 85° C. reactortemperature. 60 cm³ of 1-hexene was added to depress the density of thepolymer. The properties of the formed polymer are shown in Table IIbelow.

Example 11 (Invention) (n-propylcyclopentadienyl)(tetramethylcyclopentadienyl) Zirconium Dichloride

[0077] Polymerization:

[0078] The supported catalyst made as in Example 4 above was tested forethylene/1-hexene co-polymerization in a batch slurry reactor usingisobutane as diluent. The reactor was operated at 325 psig totalpressure, 130 psi ethylene partial pressure, and 85° C. reactortemperature. 60 cm³ of 1-hexene was added to depress the density of thepolymer. The properties of the formed polymer are shown in Table IIbelow. TABLE II Density MI MIR Productivity Example (g/cc) (I₂) (I₂₁/I₂)(g/g-hr)  4 0.9196 1.49 17.5 2213  5 0.9181 1.11 18.9 1511  6(comparative) 0.9184 0.84 31.7 1558  7 0.9170 1.03 18.8 3196  8(comparative) 0.9179 1.21 46.0 1871  9 (comparative) 0.9223 0.43 35.8 920 (see Note 1) 10 0.9234 0.22 18.3 2458 (see Note 1) 11 0.9194 0.1818.0 6490 (see Note 1)

[0079] II. Bridged Biscyclopentadienyl Catalyst Systems

[0080] Preparation of Supported Catalyst A (fluorenyl (dimethylsilyl)3-propylcyclopentadienyl Zirconium Dichloride)

[0081] Fluorenyl (dimethylsilyl) 3-propylcyclopentadienyl zirconiumdichloride, 0.092 g, was stirred with 4.0 g 30% MAO (by weight intoluene, Albemarle) and 4.0 g toluene. After complete dissolution, itwas mixed with 3.0 g SiO2 (dried at 600° C., Davison) and dried underhigh vacuum at room temperature for 12 hours.

Example 12 (Invention) fluorenyl (dimethylsilyl)3-n-propylcyclopentadienyl Zirconium Dichloride

[0082] Polymerization:

[0083] Slurry polymerizations were carried out in a 1 L. stainless steelautoclave using 800 ml isobutane as reaction solvent. Cocatalyst usedwas 1.6 mmol AlEt₃. Ethylene pressure was 120 psi and 60 ml hexene wereused. 50 mg of catalyst A was added to the reaction mixture at atemperature of 150° F. In some instances it was necessary to add 10 mmolH₂ in order to obtain the desired polymer MI. The reaction was run for40 minutes, then cooled and isobutane removed to obtain the polymer as agranular solid. TABLE III H₂ Yield Productivity Density Example (mmol)(g) (g/g-hr) (g/cc) MI MIR 12a 10   94 2823 0.9081 0.68 27.8 12b 0 1524565 0.902 0.2 26 12c 0 162 4865 0.904 0.2 31

Example 13 (Invention) fluorenyl (dimethylsilyl)2-methyl-3-benzylindenyl Zirconium Dichloride

[0084] A slurry polymerization similar to the above was performed with adifferent catalyst according to the invention. It was supported asdescribed above. The resulting MI was 9.58, the density was 0.9154 andthe MIR was 21.6.

[0085] Copolymerization of Ethylene/Hexene in Gas Phase.

Example 14 (Invention) fluorenyl (dimethylsilyl)3-n-propylcyclopentadienyl Zirconium Dichloride

[0086] Polymerizations were carried out in the above continuous gasphase unit with regular injections of the catalyst of example 12 underthe following conditions: 326 mol ppm H₂, 0.32 mol % hexene, 31.0 mol %ethylene, and a temperature of 169° F. Product characteristics arepresented in Table IV.

Example 15 (Comparative) fluorenyl (dimethylsilyl)3-methylcyclopentadienyl Zirconium Dichloride

[0087] Polymerizations were carried out in the above continuous gasphase unit with regular injections of the comparative catalyst under thefollowing conditions: 169.3 mol ppm H₂, 0.35 mol % hexene, 39.9 mol %ethylene at a temperature of 169° F. Product characteristics arepresented in Table IV. TABLE IV Productivity Density MS Example (g/g-hr)(g/cc) MI MIR CDBI (cN) 14 1529 0.9184 1.74 21.5 67.3 25.5 15(C)  7350.9138 1.08 75.2 72.5 5.1

What is claimed is:
 1. An olefin polymerization process comprisingcontacting ethylene alone or with one or more olefinically saturatedcomonomers under suitable polymerization conditions with a Group 3-6metallocene catalyst compound comprising two π bonded rings covalentlybridged to each other, said rings having one or more C₃ or greaterhydrocarbyl, hydrocarbylsilyl or hydrocarbylgermyl substituent, saidsubstituent bonded to the ring through a primary carbon atom, the totalnumber of substituents on the rings is equal to a number from 3 to 10;wherein when the number of substituents is 3 or 4, said rings areasymmetrically substituted in that the number or type of ringsubstituents on the rings are different.
 2. The process of claim 1,wherein said C₃ or greater hydrocarbyl, hydrocarbylsilyl orhydrocarbylgermyl substituent is attached at the 3 or 4 position of therings, where the ring covalently bound to the bridge is counted as the 1position.
 3. The process of claim 2, wherein said rings have 4 methylgroups on one ring and a C₃ or greater hydrocarbyl, hydrocarbylsilyl, orhydrocarbylgermyl substituent on another ring.
 4. The process of claim3, wherein said C₃ or greater primary carbon containing substituent islocated at the 3 position.
 5. The process of any of claims 1, 2, 3, or4, wherein the contacting is done under gas phase conditions.
 6. Theprocess of any of claims 1, 2, 3, or 4, wherein the contacting is doneunder slurry conditions.
 7. The process of any of claims 1, 2, 3, or 4,further comprising the step of removing an ethylene homopolymer orcopolymer from said process wherein said homopolymer or copolymer has anMIR≦35, an MWD=2-15, a CDBI≧60 and a Melt Strength≧6.0-6.0× log (MI). 8.The process of claim 7 wherein said homopolymer or said copolymer has aMelt Strength greater than or equal to 8.0-6.0× log (MI) and a MIR<25.